The invention concerns a support structure and levelling actuator arrangement for the pivoting main axle of a hillside combine.
The conventional hillside combine is supported by pivoting axles which adjust automatically to the changing slopes of a harvest field, so as to maintain the separator body laterally level. This keeps material distributed evenly across straw walkers and cleaning shoe to maintain efficient separating and cleaning action. Leveling is usually controlled by up and down movement of the front wheels using hydraulic actuators, while the rear axle pivots freely as required. The pivoting transversely extending structural member which either carries the front wheels or is connected to them and controls their movement, corresponds to the front axle of a combine and will be referred to as a balance beam.
In some combines the wheels are connected directly to the ends of the balance beam and maintained upright as the machine adjusts to changing slopes by means of a parallel linkage arrangement. In other machines, each wheel is carried on a large swing arm, each arm being pivoted on the side of the separator body, considerably behind the wheels. In this arrangement, the wheel is in fixed relation to the swing arm and hence maintained upright, and connection to the ends of the balance beam is by a short compensating connecting linkage. The majoral structural element which pivotably connects the balance beam to the separator body will be referred to as a beam box.
In a common hillside combine configuration, exemplified by Knollman and Laverda in U.S. Pat. Nos. 3,065,590 and 3,703,298 respectively, leveling is controlled by a pair of long stroke hydraulic cylinders connected close to the opposite ends of the the balance beam, and extending upright on opposite sides of the separator body, adjacent the operator's station. This upright external position for the leveling cylinders, with cylinder line of action effective close to the opposite ends of the balance beam, is mechanically efficient but no longer feasible on many modern combines. The demand for higher specific capacity within a given overall dimension of vehicle, for more versatile drive and control systems, and for greater convenience, comfort and control in operator stations has preempted this space. (Relatively) wider separator bodies, wider drive wheel tires and more room operator stations leave little room for the "external" cylinder arrangement of Knollman or Laverda.
An alternative balance beam arrangement offered by Boone in U.S. Pat. No. 3,160,221 places the leveling cylinders below the floor of the separator body, with downwardly converging lines of action effective very close to the main pivot of the balance beam. In this position the cylinders are relatively inaccessible. Cylinder specification, including stroke is determined and restricted to a great extent by the limited overall height available, and the balance beam must be designed to accommodate the relatively large bending moments resulting from the relatively long length of balance beam beyond the line of action of the cylinders.
In an axial flow rotary combine, [International Harvester] the leveling cylinder position and orientation is similar to that of Boone, but advantage is taken of the cylindrical shape of the axial flow separator casing within the separator body to extend the cylinders partially up alongside the opposite sides of the cylindrical casing, while the cylinders as a whole remain within the width of the separator body; but cylinder accessibility is still poor and maximum bending moment in the balance beam is still high. A disadvantage of both of the latter arrangements is the relatively coarse and potentially jerky leveling control action. The closeness of the cylinder line of action to the balance beam, means that a small change in cylinder stroke produces a relatively large swing of the balance beam.
Ballack, in U.S. Pat. No. 2,076,523, places the leveling cylinders below and parallel to the balance beam. But Ballack is an arrangement for a pull-type combine and one which is not readily adaptable to the driven wheels of a self-propelled machine.
The hillside combine leveling arrangements referred to above are all solutions to particular machine requirements and space availability, and do not have universal application for converting a level-land combine to a hillside combine.